java Gson：不是 JSON 对象
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Gson: Not a JSON Object
提问by marknorkin
I have the following String passed to server:
我将以下字符串传递给服务器：
{
"productId": "",
"sellPrice": "",
"buyPrice": "",
"quantity": "",
"bodies": [
{
"productId": "1",
"sellPrice": "5",
"buyPrice": "2",
"quantity": "5"
},
{
"productId": "2",
"sellPrice": "3",
"buyPrice": "1",
"quantity": "1"
}
]
}
which is a valid json for http://jsonlint.com/
这是http://jsonlint.com/的有效 json
I want to get the bodies array field.
我想获取 body 数组字段。
That's how I'm doing it:
这就是我的做法：
Gson gson = new Gson();
JsonObject object = gson.toJsonTree(value).getAsJsonObject();
JsonArray jsonBodies = object.get("bodies").getAsJsonArray();
But on the second line I'm getting exception listed below:
但在第二行，我得到下面列出的异常：
HTTP Status 500 - Not a JSON Object: "{\"productId\":\"\",\"sellPrice\":\"\",\"buyPrice\":\"\",\"quantity\":\"\",\"bodies\":[{\"productId\":\"1\",\"sellPrice\":\"5\",\"buyPrice\":\"2\",\"quantity\":\"5\"},{\"productId\":\"2\",\"sellPrice\":\"3\",\"buyPrice\":\"1\",\"quantity\":\"1\"}]}"
How to do it properly then ?
那该怎么做呢？
回答by Sotirios Delimanolis
Gson#toJsonTreejavadocstates
This method serializes the specified object into its equivalent representation as a tree of
JsonElements.
此方法将指定的对象序列化为
JsonElements树的等效表示形式。
That is, it basically does
也就是说，它基本上是
String jsonRepresentation = gson.toJson(someString);
JsonElement object = gson.fromJson(jsonRepresentation, JsonElement.class);
A Java Stringis converted to a JSON String, ie. a JsonPrimitive, not a JsonObject. In other words, toJsonTreeis interpreting the content of the Stringvalue you passed as a JSON string, not a JSON object.
JavaString转换为 JSON 字符串，即。一个JsonPrimitive，不是一个JsonObject。换句话说，toJsonTree是将String您传递的值的内容解释为 JSON 字符串，而不是 JSON 对象。
You should use
你应该使用
JsonObject object = gson.fromJson(value, JsonObject.class);
directly, to convert your Stringto a JsonObject.
直接将您的转换String为JsonObject.
回答by bbill
I have used the parsemethod as described in https://stackoverflow.com/a/15116323/2044733before and it's worked.
我之前使用过https://stackoverflow.com/a/15116323/2044733 中parse描述的方法并且它有效。
The actual code would look like
实际代码看起来像
JsonParser jsonParser = new JsonParser();
jsonParser.parse(json).getAsJsonObject();
From the docsit looks like you're running into the error described where your it thinks your toJsonTreeobject is not the correct type.
从文档看来，您遇到了所描述的错误，它认为您的toJsonTree对象类型不正确。
The above code is equivalent to
上面的代码等价于
JsonObject jelem = gson.fromJson(json, JsonElement.class);
as mentioned in another answer here and on the linked thread.
如此处和链接线程上的另一个答案所述。
回答by JoseQ
What about JsonArray jsonBodies = object.getAsJsonArray("bodies");
怎么样JsonArray jsonBodies = object.getAsJsonArray("bodies");
